Field of the Invention
The present invention relates to a medical acoustic coupler to be interposed between an ultrasonic probe and the object being examined at a time of ultrasound imaging by a diagnostic ultrasound imaging apparatus, and to the diagnostic ultrasound imaging apparatus including the medical acoustic coupler.
Description of the Related Art
Diagnostic ultrasound imaging apparatuses of a certain kind are now widely used. A diagnostic ultrasound imaging apparatus of this certain kind transmits ultrasound to a living organism as the object being examined, receives and processes echo signals, and generates images of cross-sections of the object being examined. In such a diagnostic ultrasound imaging apparatus, ultrasonic probes each having an ultrasound transmission/reception surface that transmits and receives ultrasound to and from the object being examined are provided and are normally connected to the main unit of the diagnostic ultrasound imaging apparatus. An ultrasonic pulse is transmitted from the ultrasound transmission/reception surface of an ultrasonic probe brought into contact with the surface of the object being examined, and waves reflected from the object being examined are detected by the ultrasonic probe. The main unit of the diagnostic ultrasound imaging apparatus analyzes the reflected waves, and generates images by performing ultrasound imaging on the object being examined.
If the contact between the ultrasound transmission/reception surface of the ultrasonic probe and the surface of the object being examined is insufficient during the examination, a layer of air might be formed between the ultrasound transmission/reception surface and the surface of the object being examined. If a layer of air is formed between the ultrasound transmission/reception surface and the surface of the object being examined, most ultrasound is reflected by the layer of air, and ultrasound hardly enters the living organism, resulting in incorrect diagnosis. In a case where a superficial site of the object, such as a muscle or a tendon, is examined, ultrasonic beams need to be focused onto the superficial site. In such a case, a medium with a certain thickness is interposed between the ultrasonic probe and the surface of the object being examined, to make adjustment so that the distance between the ultrasonic probe and the site being examined becomes substantially equal to the focus length of ultrasound. In a case where a joint that is bent due to rheumatism or the like is examined, an ultrasonic probe tightly pressed against the joint might cause the patient a great pain due to the uneven surface of the joint. So as not to cause the patient such a pain, an elastic medium should be interposed between the ultrasonic probe and the patient.
In view of the above circumstances, at a time of examination using a diagnostic ultrasound imaging apparatus, an acoustic medium (an acoustic coupler) that has appropriate elasticity and acoustic impedance may be interposed between an ultrasonic probe and the surface of the object being examined. An example of the acoustic medium that has appropriate elasticity and acoustic impedance is a medical acoustic coupler disclosed in JP 2014-193275 A.
JP 2014-193275 A discloses a medical acoustic coupler including: a gel-like layer that has a predetermined thickness and a size corresponding to the ultrasound emitting surface, and is an elastic member that can adhere to the ultrasound emitting surface; and a film layer formed on the contact surface to be brought into contact with a test subject.
In the medical acoustic coupler disclosed in JP 2014-193275 A, the gel-like layer has a predetermined adhesive force. Thus, the medical acoustic coupler is appropriately attached to an ultrasonic probe by virtue of the adhesive force. However, after the medical acoustic coupler is used multiple times, or because dust or the like adheres to the adhesive surface, the adhesive force of the gel-like layer becomes gradually smaller. Due to such a decrease in the adhesive force, the medical acoustic coupler is not fixed to an ultrasonic probe (or is not easily fixed to an ultrasonic probe), and needs to be replaced with a new medical acoustic coupler even if the transmission characteristics of the ultrasound of the medical acoustic coupler have not degraded.